Comparison of the composting process using ear corn residue and three other conventional bulking agents during cow manure composting under high‐moisture conditions

To elucidate the characteristics of ear corn residue as a bulking agent, the composting process using this residue was compared with processes using three other conventional materials such as sawdust, wheat straw and rice husk, employing a bench-scale composting reactor. As evaluated via biochemical oxygen demand (BOD), ear corn residue contains 3.3 and 2.0 times more easily digestible materials than sawdust and rice husk, respectively. In addition, mixing ear corn residue with manure resulted in reduced bulk density, which was the same as that of wheat straw and was 0.58 and 0.67 times lower than that of sawdust and a rice husk mixture, respectively. To evaluate temperature generation during the composting process, the maximum temperature and area under the temperature curve (AUCTEMP) were compared among the mixed composts of four bulking agents. Maximum temperature (54.3°C) as well as AUCTEMP (7310°C●h) of ear corn residue were significantly higher than those of sawdust and rice husk (P<0.05), and they are similar to that of wheat straw mixed compost. Along with the value of AUCTEMP, the highest organic matter losses of 31.1% were observed in ear corn residue mixed compost, followed by wheat straw, saw dust and rice husk.